Got AC 0.015 with this magic code

#define forn(i,n) for (int i = 0; i < (int)(n); i++)
typedef long double ld;
ld g = 9.81l;
int main() {
    ld l, h, w;
    cin >> l >> h >> w;
    l /= 100, h /= 100, w *= acosl(0) / 15;
    ld t = 0;
    forn (i, 1000) {
        ld d = fabsl(sinl(w * t) * l / 2);
        //g x^2 /2 + (x-t)wl/2 + d = h
        //x^2 g/2 + x wl/2 - wlt/2+d-h = 0
        t = (-w * l / 2 + sqrtl(w * w * l * l / 4 + 2 * g * (w * l * t / 2 - d + h))) / g;
    }
    cout << ((cosl(w * t) > 0) ? "butter": "bread");
}

the next moment found the normal solution.

Edited by author 19.10.2011 12:17